More Detained in British Soldier's Killing

LONDON—As police made more arrests here Saturday evening in their widening probe of Wednesday's brutal killing of a British soldier near a military barracks in southeast London, a political debate intensified over whether U.K. security services could have stopped the attack.

The Metropolitan Police said they arrested two men, ages 24 and 28, at a residential address in southeast London, while a 21-year-old man was arrested on the street. Two of the men were taken into custody with the use of a Taser but weren't...